Oxygen Saturation and Postoperative Mortality in Patients With Acute Ischemic Stroke Treated by Endovascular Thrombectomy.

BACKGROUND: Monitored anesthesia care (MAC) and general anesthesia (GA) with endotracheal intubation are the 2 most used techniques for patients with acute ischemic stroke (AIS) undergoing endovascular thrombectomy. We aimed to test the hypothesis that increased arterial oxygen concentration during reperfusion period is a mechanism underlying the association between use of GA (versus MAC) and increased risk of in-hospital mortality. METHODS: In this retrospective cohort study, data were collected at the Cleveland Clinic between 2013 and 2018. To assess the potential mediation effect of time-weighted average oxygen saturation (Spo2) in first postoperative 48 hours between the association between GA versus MAC and in-hospital mortality, we assessed the association between anesthesia type and post-operative Spo2 tertiles (exposure-mediator relationship) through a cumulative logistic regression model and assessed the association between Spo2 and in-hospital mortality (mediator-outcome relationship) using logistic regression models. Confounding factors were adjusted for using propensity score methods. Both significant exposure-mediator and significant mediator-outcome relationships are needed to suggest potential mediation effect. RESULTS: Among 358 patients included in the study, 104 (29%) patients received GA and 254 (71%) received MAC, with respective hospital mortality rate of 19% and 5% (unadjusted P value <.001). GA patients were 1.6 (1.2, 2.1) (P < .001) times more likely to have a higher Spo2 tertile as compared to MAC patients. Patients with higher Spo2 tertile had 3.8 (2.1, 6.9) times higher odds of mortality than patients with middle Spo2 tertile, while patients in the lower Spo2 tertile did not have significant higher odds compared to the middle tertile odds ratio (OR) (1.8 [0.9, 3.4]; overall P < .001). The significant exposure-mediator and mediator-outcome relationships suggest that Spo2 may be a mediator of the relationship between anesthetic method and mortality. However, the estimated direct effect of GA versus MAC on mortality (ie, after adjusting for Spo2; OR [95% confidence interval {CI}] of 2.1 [0.9-4.9]) was close to the estimated association ignoring Spo2 (OR [95% CI] of 2.2 [1.0-5.1]), neither statistically significant, suggesting that Spo2 had at most a modest mediator role. CONCLUSIONS: GA was associated with a higher Spo2 compared to MAC among those treated by endovascular thrombectomy for AIS. Spo2 values that were higher than the middle tertile were associated with higher odds of mortality. However, GA was not significantly associated with higher odds of death. Spo2 at most constituted a modest mediator role in explaining the relationship between GA versus MAC and mortality.

The relative effects of dexmedetomidine and propofol on cerebral blood flow velocity and regional brain oxygenation: A randomised noninferiority trial.

BACKGROUND: Dexmedetomidine constricts cerebral blood vessels without a concomitant reduction in cerebral metabolic oxygen consumption. Its safety as a sedative in patients with neurological diseases thus remains uncertain. OBJECTIVE: Our primary objective was to test the hypothesis that dexmedetomidine is noninferior to propofol as regards cerebral blood flow (CBF) velocity and brain oxygenation. DESIGN: Unblinded randomised trial. SETTING: Cleveland Clinic Hospital, Cleveland, from November 2010 to July 2013. PATIENTS: Forty-four patients scheduled for insertion of a deep-brain stimulating electrodes. INTERVENTIONS: Patients were randomised to receive either dexmedetomidine or propofol sedation during deep-brain stimulating electrode insertion. MAIN OUTCOME MEASURES: Intraoperative CBF velocity was measured with transcranial Doppler, and brain oxygenation was assessed with near-infrared spectroscopy. Noninferiority of dexmedetomidine to propofol was defined as a less than 20% difference in means. RESULTS: Twenty-three patients were given dexmedetomidine and 21 propofol. Baseline characteristics and operative management were similar in each group. Dexmedetomidine was noninferior to propofol on both CBF and brain oxygenation, confirming our primary hypothesis. For cerebral flood flow, the estimated ratio of means (dexmedetomidine/propofol) was 0.94 [90% CI: 0.84 to 1.05], P = 0.011 for noninferiority. For brain oxygenation, the estimated ratio of means was 0.99 [90% CI: 0.96 to 1.02], P < 0.001 for noninferiority. Superiority was not found for either primary outcome. Dexmedetomidine provided deeper sedation than propofol, with a difference of medians of 1 [90% CI: 0 to 2], P < 0.001 on the Observer's Assessment of Alertness/Sedation scale. No significant differences were observed in pulsatility index, cerebral perfusion pressure, number of hypertensive or apnoeic episodes. CONCLUSION: Regional brain oxygenation and CBF velocity are comparably preserved during dexmedetomidine and propofol sedation. Thus, the use of dexmedetomidine in patients with movement disorders appears reasonable. TRIAL REGISTRATION: The trial was registered at ClinicalTrials.gov (NCT 01200433).

The renin angiotensin system and the brain: New developments.

The traditional renin-angiotensin system (RAS) is indispensable system in adjusting sodium homeostasis, body fluid volume, and controlling arterial blood pressure. The key elements are renin splitting inactive angiotensinogen to yield angiotensin (Ang-I). Ang-1 is then changed by angiotensin-1 converting enzyme (ACE) into angiotensin II (Ang-II). Using PubMed, Google Scholar, and other means, we searched the peer-reviewed literature from 1990 to 2013 for articles on newly discovered findings related to the RAS, especially focusing on how the system influences the central nervous system (CNS). The classical RAS is now considered to be only part of the picture; the discovery of additional RAS pathways in the brain and elsewhere has yielded a vastly improved understanding of how the RAS influences the CNS. Newly discovered effects of the RAS on brain tissue include neuroprotection, cognition, and cerebral vasodilation. A number of brain biochemical pathways are influenced by the brain RAS. Within various pathways, there are potential opportunities for classical pharmacologic interventions as well as the possibility of controlling gene expression.

Intraoperative Hypotension During Second Stage of Deep Brain Stimulator Placement: Same Day versus Different Day Procedures.

BACKGROUND: We evaluated blood pressure management associated with implantable pulse generator (IPG) procedure on same day (SD) versus different day (DD) from deep brain stimulation (DBS) placement. METHODS: A retrospective chart review of 99 records for vasopressors given during IPG using a negative binomial regression model was performed. An association between SD versus DD, cumulative vasopressor dose, and minimum and maximum mean arterial pressure (MAP) were sought. RESULTS: No significant association between SD versus DD DBS and the number of times vasopressors were given during stage II, estimated ratio of means (CI) of 1.8 (0.9-3.5); P = 0.07. Day of stage II had no association with the cumulative dose of vasopressor given during stage II, with an estimated difference in means (CI) of 2.4 (-0.4 to 5.3). The SD group had a significantly lower mean of minimum stage II MAP compared with DD, with an estimated difference in means (CI) of -10.5 (-17.4 to -3.5; P < 0.001). There was no association with maximum stage II MAP, with an estimated difference in means (CI) of -2.8 (-17.6 to 12.0; P = 0.63). CONCLUSION: No difference in intraoperative vasopressor use was found between SD versus DD IPG placement, but the SD group had a significantly lower minimum MAP.

Factors predicting incremental administration of antihypertensive boluses during deep brain stimulator placement for Parkinson's disease.

Hypertension is common in deep brain stimulator (DBS) placement predisposing to intracranial hemorrhage. This retrospective review evaluates factors predicting incremental antihypertensive use intraoperatively. Medical records of Parkinson's disease (PD) patients undergoing DBS procedure between 2008-2011 were reviewed after Institutional Review Board approval. Anesthesia medication, preoperative levodopa dose, age, preoperative use of antihypertensive medications, diabetes mellitus, anxiety, motor part of the Unified Parkinson's Disease Rating Scale score and PD duration were collected. Univariate and multivariate analysis was done between each patient characteristic and the number of antihypertensive boluses. From the 136 patients included 60 were hypertensive, of whom 32 were on angiotensin converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB), told to hold on the morning of surgery. Antihypertensive medications were given to 130 patients intraoperatively. Age (relative risk [RR] 1.01; 95% confidence interval [CI] 1.00-1.02; p=0.005), high Joint National Committee (JNC) class (p<0.0001), diabetes mellitus (RR 1.4; 95%CI 1.2-17; p<0.0001) and duration of PD >10 years (RR 1.2; 95%CI 1.1-1.3; p=0.001) were independent predictors for antihypertensive use. No difference was noted in the mean dose of levodopa (p=0.1) and levodopa equivalent dose (p=0.4) between the low (I/II) and high severity (III/IV) JNC groups. Addition of dexmedetomidine to propofol did not influence antihypertensive boluses required (p=0.38). Intraoperative hypertension during DBS surgery is associated with higher age group, hypertensive, diabetic patients and longer duration of PD. Withholding ACEI or ARB is an independent predictor of hypertension requiring more aggressive therapy. Levodopa withdrawal and choice of anesthetic agent is not associated with higher intraoperative antihypertensive medications.

Perioperative management of intracranial aneurysm and subarachnoid hemorrhage.

Stroke is the third leading cause of death and the leading cause of disability in contemporary society. Aneurysmal subarachnoid hemorrhage (aSAH) is a hemorrhagic stroke which accounts for 7% of all stroke cases and 22 to 25% of cerebrovascular deaths. Aneurysmal subarachnoid hemorrhage is a very complex disease and many controversies on its pathophysiology and management have not yet been settled. The aim of this review is to present the most recent evidence-based advances in the pathophysiology and perioperative management of aSAH.

A case series discussing the anaesthetic management of pregnant patients with brain tumours.

Pregnancy may aggravate the natural history of an intracranial tumour, and may even unmask a previously unknown diagnosis. Here we present a series of seven patients who had brain tumours during pregnancy. The aim of this case series is to characterize the current perioperative management and to suggest evidence based guidelines for the anaesthetic management of pregnant females with brain tumours. This is a retrospective study. Information on pregnant patients diagnosed with brain tumours that underwent caesarean section (CS) and/or brain tumour resection from May 2003 through June 2008 was obtained from the Department of General Anaesthesia and the Rose Ella Burkhardt Brain Tumour & Neuro-Oncology Centre (BBTC) at the Cleveland Clinic, OH, USA. The mean age was 34.5 years (range 29-40 years old). Six patients had glioma, two of whom had concomitant craniotomy and CS. Six cases had the tumour in the frontal lobe. Four cases were operated on under general anaesthesia and three underwent awake craniotomy. The neonatal outcomes of the six patients with elective or emergent delivery were six viable infants with normal Apgar scores. Pregnancy was terminated in the 7th patient. In conclusion, good knowledge of the variable anesthetic agents and their effects on the fetus is very important in managing those patients.

The use of dexmedetomidine in anesthesia and intensive care: a review.

The alpha-2 agonist dexmedetomidine is being increasingly used for sedation and as an adjunctive agent during general and regional anesthesia. It is used in a number of procedures and clinical settings including neuroanesthesia, vascular surgery, gastrointestinal endoscopy, fiberoptic intubation, and pediatric anesthesia. The drug is also considered a nearly ideal sedative agent in the intensive care setting. However, the drug frequently produces hypotension and bradycardia, and also decreases cerebral blood flow without concomitantly decreasing the cerebral metabolic rate for oxygen. This review discusses recent advances in the use of dexmedetomidine in anesthesia and intensive care settings, as well as discuss potential problems with its use.

Gender rather than choice of intermediate duration opioids affects emergence after craniotomy for large intracranial tumors.

BACKGROUND: Opioid-based anesthetic techniques are commonly used during neurosurgical procedures. In the present randomized prospective study, we studied emergence after 4 anesthetic regimens combining intermediate duration opioids with isoflurane and nitrous oxide (N(2)O), in patients undergoing craniotomy for large (> 30 mm diameter with intracranial mass effect) intracranial tumors. METHODS: One hundred seven patients were randomized into 4 groups: Group A: fentanyl (≤ 5 µg/kg) + isoflurane (≤ 1 minimum alveolar concentration [MAC]), Group B: sufentanil (1-2 µg/kg plus infusion) + isoflurane (≤ 0.5 MAC), Group C: sufentanil (2 µg/kg bolus only) + isoflurane (≤ 1 MAC), and Group D: alfentanil (100 µg/kg plus infusion) + isoflurane (≤ 0.5 MAC). Boluses were administered as divided doses during induction, laryngoscopy, head pinning, and incision. Blood pressure was controlled at ±25% of baseline levels. All infusions were discontinued at the start of dural closure. Emergence was assessed using a mini-neurologic examination consisting of 7 questions. Groups were compared on time to emergence using survival analysis methods. RESULTS: The groups did not differ regarding extubation time, which occurred at a median of 4 to 6 minutes across groups after discontinuing N(2)O. The median emergence time ranged from 15 to 22.5 minutes and did not differ among groups. However, across all groups more women had emerged by 30 minutes compared with men (83% vs 57%, P â€Š=  .002). The median emergence time in women was found to be significantly shorter (0-15 minutes) than in men (15-30 minutes) (P â€Š=  .012). CONCLUSIONS: No between-group differences in emergence time were observed; the study was stopped early because of evidence that no differences were likely to be found if the study were continued. However, in a post hoc analysis, female gender was associated with faster emergence.

Use of α(2)-Agonists in Neuroanesthesia: An Overview.

α(2)-Agonists are a novel class of drugs with mechanisms of action that differ from other commonly used anesthetic drugs. They have neuroprotective, cardioprotective, and sedative effects. These unique characteristics make them potentially useful during neuroanesthesia and intensive care. We review the effects of dexmedetomidine on cerebral blood flow and cerebral metabolism, along with recent advances in using α(2)-agonists in neuroanesthesia and neurointensive care.

Delayed awakening in dystonia patients undergoing deep brain stimulation surgery.

We aimed to identify the incidence, duration and causes of delayed emergence from anesthesia in patients with dystonia undergoing surgery for deep brain stimulation (DBS) placement. A retrospective review of patients with dystonia who underwent DBS placement was conducted and the following characteristics were noted: age, gender, comorbid conditions, American Society of Anesthesiologists classification, anesthetic agents used, amount of initial dose, amount of infusion dose, duration of the infusion and the time needed for emergence. Twenty-four patients underwent 33 DBS procedures for dystonia. Propofol was administered to 21 patients, in 29 of the 33 procedures. Dexmedetomidine was administered to three patients, in four procedures. The average propofol loading dose was 0.7mg/kg, and the infusion rate was 80microg/kg per minute (min), for an average duration of 89min. The average time of emergence was 36min. Only 31% of patients emerged from propofol anesthesia during the expected time frame, 69% of patients had some degree of delayed emergence, and 24% had a significant delay in emergence. Delayed emergence was more common in younger patients due to the higher loading doses these patients received. This study shows a 69% incidence of delayed emergence in dystonia patients undergoing DBS surgery. It also suggests an association between delayed emergence and younger patients who receive higher loading doses. A possible cause of delayed emergence is excessive anesthetic potentiation of the low output pallidal state in dystonia which may depress the pallido-thalamo-cortical circuitry. Delayed emergence could also result from depression of the previously affected ventral pallidal inputs to the septo-hippocampal system that mediates general anesthesia and awareness. Complex neurotransmitter disturbances may also be involved.

Dosing of remifentanil to prevent movement during craniotomy in the absence of neuromuscular blockade.

BACKGROUND: In neuroanesthesia practice, muscle relaxants may at times need to be avoided to facilitate intraoperative motor pathway monitoring. Our study's objective was to determine the optimal dose of remifentanil required to prevent movement after neurosurgical stimulation. METHODS: After Institutional Review Board approval and written informed consent, 132 patients undergoing elective craniotomy randomly received one of 12 remifentanil dose regimens (0.10 to 0.21 microg/kg/min). Remifentanil was started before induction with propofol and succinylcholine. Anesthesia was maintained with isoflurane (0.6% end-tidal) in air/oxygen. During the study, movement was assessed on predetermined criteria by the anesthesiology, nursing, and neurosurgical teams. Heart rate and blood pressure were recorded every 5 minutes. We assessed the relationship between movement, hypotension, bradycardia, and dose using probit analysis and logistic regression. RESULTS: Sixty-five percent of the patients moved in response to surgical stimuli [95% confidence interval (CI): 49%-79%] at a remifentanil infusion rate of 0.10 microg/kg/min, and movement decreased to 21% (95% CI: 11-35) at 0.21 microg/kg/min. The probability of movement was 50% at an infusion rate (95% CI) of 0.13 (0.10 to 0.15) microg/kg/min remifentanil and decreased to 25% at an infusion rate of 0.19 (0.17 to 0.29) microg/kg/min. The probability of hypotension and bradycardia was 50% at 0.13 (0.10 to 0.15) microg/kg/min and 0.17 (0.15 to 0.21) microg/kg/min, respectively. CONCLUSIONS: Higher doses of remifentanil lessen the risk of movement in the absence of muscle relaxants with surgical stimulation for elective craniotomy. Hypotension and bradycardia were common at higher doses. Even at the maximum dose (0.21 mcg/kg/min) there was a 20% chance of movement. Adjunctive therapy is needed to ablate movement reliably, and to counteract the hypotensive effect of remifentanil. These findings may be helpful for clinicians administering remifentanil and isoflurane during procedures, where muscle relaxants may not be desirable.

Patient-controlled epidural analgesia (PCEA) for postoperative pain control after lumbar spine surgery.

Spine surgery remains one of the most common procedures for patients with a wide variety of spine disorders. Postoperative pain after major spine surgery is moderate to severe. We retrospectively reviewed 245 medical records of adult patients undergoing major spine surgery who received either patient-controlled epidural analgesia based on local anesthetics and opioids or patient-controlled intravenous analgesia as postoperative pain management. Several outcomes were analyzed including pain intensity, opioid consumption, time to endotracheal extubation, the incidence of deep venous thrombosis, and length of stay in the hospital. We found that the use of patient-controlled epidural analgesia provided better postoperative analgesia [median (quartiles) verbal analog scale score of 4 (3, 5) vs. 5 (3, 6)] and decreased the amount of opioid consumption postoperatively [median of 0 mg (0, 3) vs. 35 mg (0, 150)] compared with patient-controlled intravenous analgesia. Also, a substantially higher number of patients in the patient-controlled intravenous group required opioids as rescue analgesia. Incidences of deep venous thrombosis, operating room extubation, and length of stay in the hospital were not associated with the analgesic technique. The results of this study suggest that the use of neuroaxial analgesia for the management of postoperative pain associated with major spine surgery may have some beneficial properties over intravenous analgesia. The use of a reduced amount of opioids by patients with epidural analgesia may be relevant because of potential fewer side effects mainly in elderly patients. Several limitations related to the retrospective nature of the study are described. Prospective randomized-controlled trials are needed to understand and elucidate the optimum regimen of postoperative pain management after major spine surgery.

Perioperative events during deep brain stimulation: the experience at cleveland clinic.

BACKGROUND: Deep brain stimulation (DBS) of the basal ganglia is an evolving technique for managing intractable movement disorders such as those due to Parkinson disease. We conducted a retrospective review of the DBS procedures that have been performed at our institution to determine the frequency and types complications that occurred. METHODS: After Institutional Review Board approval, 258 procedures involving 250 patients were retrospectively reviewed. Univariate analysis using the chi test for the categorical variables and a t-test for the continuous variables was performed on patients with and without complications to determine potential risk factors. RESULTS: The most common anesthesia technique used for DBS procedures was monitored anesthesia care using a propofol infusion during the early part of the case. Airway, respiratory, neurologic, and psychologic/psychiatric complications occurred. Age was found to be an independent risk factor for complications during DBS. CONCLUSION: This retrospective study demonstrates that age is an independent risk factor for complications during DBS procedures. Monitored anesthesia care using propofol seems to be a safe technique for DBS procedures; however, dexmedetomidine can also be used.

Perioperative complications of blood brain barrier disruption under general anesthesia: a retrospective review.

Blood brain barrier disruption enhances drug delivery in primary central nervous system lymphoma. In this study, we report adverse events that were encountered intraoperatively and in the postoperative period in these patients. A retrospective analysis of 17 patients documenting demographic data, preprocedure medical history, intraoperative, and postoperative anesthetic complications was conducted between January 2002 and December 2004. Seventeen patients underwent 210 treatments under general anesthesia with a mean of 12.4+/-7.2 treatments per patient. Focal seizures occurred in 13% of patients. Generalized motor seizures occurred in 4 treatment sessions in 2 different patients. The incidence of seizures was significantly higher when the internal carotid artery was used for injection, as opposed to the vertebral artery (20.8% and 6.02%, respectively, P=0.0034). Tachycardia associated with ST segment depression occurred 9 times (4.3%) in 3 patients. One patient had significant ST segment elevation (more than 1.5 mm). Transient cerebral vasospasm after methotrexate injection occurred in 9% of patients. Postoperative nausea and vomiting were observed in 11.9% of patients. After emergence, lethargy and obtundation occurred in 7.6% of the cases. The incidence of postoperative headache and reversible motor deficits was 6% and 3.8%, respectively. Our review highlights the problems that were encountered during blood brain barrier disruption under anesthesia and in the postoperative period. Further prospective studies are required for comprehensive evaluation of intraprocedure and postprocedure complications that will allow development of an optimal anesthetic plan and will improve patient outcome by preventing potential complications.

Massive pulmonary thromboembolism during elective spine surgery.

Massive pulmonary thromboembolism (PTE) is a condition that can still be seen in the operating room despite the use of thromboprophylaxis. A high degree of suspicion of this condition is necessary to achieve an early diagnosis and a rapid treatment to improve patient outcome. We report on a 27-year-old patient who sustained a massive PTE while undergoing a second-stage anterior release and posterior fusion of his thoracolumbar spine for idiopathic scoliosis.

Dexmedetomidine and awake fiberoptic intubation for possible cervical spine myelopathy: a clinical series.

For many anesthesiologists, awake fiberoptic endotracheal intubation (AFOBI) is the preferred method of intubation when treating patients with symptoms or signs of cervical spinal cord compression. The advantage of this method is to minimize cervical spine movements that could contribute to neurologic impairment. In patients who are anxious or poorly cooperative, adequate sedation in addition to topicalization of the airway may be key to minimize patient discomfort and assist in successful intubation, but imposes the risk of respiratory depression. Dexmedetomidine has the advantage of producing sedation without a significant decrease in respiratory drive. We are now reporting our experience of a series of AFOBI using dexmedetomidine for sedation. A retrospective chart review was conducted on the anesthetic records of patients, who had undergone an awake fiberoptic endotracheal intubation (AFOBI) using dexmedetomidine for sedation. These were patients in whom AFOBI was indicated because of signs or symptoms of cervical spinal cord compression. Dexmedetomidine provided adequate sedation. We did not encounter any loss of airway or airway obstruction during the intubation. The patients had excellent cooperation for post-intubation neurologic examination. Thirteen patients developed transient hypotension after induction of general anesthesia that was managed with boluses of phenylephrine or ephedrine.

Anesthetic management of a patient with congenital methemoglobinemia.

A knowledge of congenital methemoglobinemia is essential to deliver a safe anesthetic to this group of patients. We report the case of a 33-year-old patient with congenital methemoglobinemia undergoing a gynecological procedure, and discuss the anesthetic implications. The etiology, pathophysiology, classification, diagnosis, clinical manifestations, anesthetic considerations, treatment options, and postoperative management are also discussed.